The Niffler has a long snout and a coat of black, fluffy fur. They are attracted to shiny things, like jewels, money, etc. This makes them great at locating treasure. A Nifflers pouch can hold many items, this can be helpful when they are collecting shiny things. Because they are attracted to shiny things, it also means that they could wreck havoc if they were kept, or set loose, inside. An example of this would be in 1926, when Newt Scamander's Niffler escaped twice from his suitcase, and tried to rob both the Steen National Bank and a jewel shop of numerous valuables. Nifflers are gentle by nature, and can even be affectionate towards their owners. However, they could destroy objects when looking for shiny or sparkly things. because of this it was strongly advised not to keep them as a house pet. It was also implied that Nifflers could turn vicious if provoked, due to the time a Niffler tried to take a chunk ot of Dolores Umbridge's leg when it was released into her office. The Niffler is native to Great Britain, and used to be kept by Goblins, who used them to burrow for treasure. In the fourth book of Harry Potter, Rubeus Hagrid brought Nifflers to Care Of Magical Creatures class, and Ron Weasley asked if they could buy Nifflers as pets. Hagrid said that it was not suggested to have Nifflers kept as house pets, because they could create chaos. However, Hagrid's answer was not a definate "no". This means that there is a very good chance that wizards could purchase Nifflers as pets.

Sources: my brain and wiki fandom